I'm no expert on long haul, but do this: Go put a chair inside your closet and turn out the light. Now turn on the vacuum cleaner and sit there for 11 hours. Fun huh? Your choice is simple. If you like the money and travel, go for the 747-400 position. If you are truly in love with flying, (lots of takeoffs and landings) go for the 737 position. Also consider this: What does your resume look like in two years if either carrier furloughs you? Much better off with the command time brother.
Cheers!
DAN